1. Field of the Invention
The present invention relates to a uterovaginal tool for treating cancer of the uterine cervix and, more particularly, to such a tool having a slender tube first inserted into the vagina followed by an easily attached vaginal retainer to keep the tube correctly positioned within the uterus.
2. Discussion of the Prior Art
Radiotherapy is and has been the treatment of choice in the management of invasive cancer of the uterine cervix for many years. A high percentage of cases can be cured when the disease is limited to the uterus and vagina. The risk of a tumor recurrence or therapeutic complication depends primarily on the ability of the radiotherapist to produce a dose distribution which eradicates the tumor and yet does not exceed normal tissue tolerances.
In some instances, linear source uterovaginal applicators are used in preference to nonlinear source applicators and have the following advantages:
A. Simpler and easier afterloading with radioactive sources; PA1 B. Dose homogeneity around the entire circumference of the vaginal vault; and PA1 C. Greater flexibility in fitting different anatomical sizes and disease distributions.
One of the basic principles of radiation treatment with a cylindrical applicator having a central linear source is to employ the greatest treatment distance (cylinder radius) which the patient's anatomy will permit. In this way, there is not such a precipitous fall in dose below the surface and the effective thickness of tissue which can be adequately irradiated is maximal.
Conventional linear source uterovaginal applicators are in the form of one-piece cylinders of varying lengths and diameters which slip over a tube (tandem) containing the central linear source and passing through the vagina into the uterine cavity. The diameter of the vaginal cylinder which may be used is limited by the size the vaginal introitus, which in most instances is less than that of the vaginal vault.
My prior U. S. Pat. 4,244,357 discloses a linear source uterovaginal applicator which has proven to be a good tool for the treatment of uterine cancer but was found to have some shortcomings. That patent described a tube (tandem) insertable through the vagina into the uterine cavity and a retainer for the tandem comprising two half cylinders (bivoids) for occupying the vaginal cavity. The bivoids were individually insertable through the vaginal introitus. Upon assembly they would be held together by the vagina walls and cooperate to hold the tandem in place by an interlocking device. Having individually insertable bivoids allowed the physician to use a vaginal cylinder (two bivoids) of a diameter limited only by the size of the vaginal cavity--not the vaginal introitus.
However, the interlocking structure is located within the bivoids, and because the bivoids become enveloped within the vaginal cavity during use, the physician is unable to see if the bivoids are properly locked to the tandem. Furthermore, my earlier invention included an apparatus for inserting the bivoids which contained many separate parts. Consequently, additional time and effort was needed to attach the handles to and disconnect them from the bivoids.